[time-nuts] Frequency referenced temperature regulator

[Bob Camp]

Hi

The crystal in the temperature probes was an LC cut. There are a number of
temperature dependant cuts out there for BAW's. SAW's have their own
families of cuts. 

One of the drivers for running the probes at the frequency they chose was
the small crystal package they wanted to use. Tough to fit a 5 MHz 3rd
overtone in a TO-5 package.

Bob 

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of John Ackermann N8UR
Sent: Monday, November 08, 2010 11:26 AM
To: Discussion of precise time and frequency measurement
Cc: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Frequency referenced temperature regulator

I've never looked.  The original HP Journal article talked about the
characteristics of the crystal.  I think it's called an L cut.  The
frequency used was around 26 MHz because that yielded an easy Hz/degree
ratio.

On Nov 8, 2010, at 10:21 AM, Brooke Clarke <brooke at pacific.net> wrote:

> Hi John:
> 
> Is there a source of crystals cut for temperature measurements?
> 
> Have Fun,
> 
> Brooke Clarke
> http://www.PRC68.com
> 
> 
> John Ackermann N8UR wrote:
>> Sounds like the way the HP 2804 quartz thermometer works.  HP came up
with a special crystal cut that was very linear with temp, and I suspect the
hardest part of your idea might be the linearity of the tempco of your
crystal.  But you could characterize that and store in a correction table.
>> 
>> John
>> 
>> On Nov 8, 2010, at 10:04 AM, "Poul-Henning Kamp"<phk at phk.freebsd.dk>
wrote:
>> 
>>   
>>> I'm contemplating building a small temperature control enclosure for
>>> testing various electronics.
>>> 
>>> I have a handful of peltiers suitable for the purpose, and was
>>> pondering the right control mechanism.
>>> 
>>> Most people would reach for a NTC, put it in a wien-brige etc etc.
>>> 
>>> But since I happen to have access to much more stable frequencies
>>> than voltages, I thought of a different way:
>>> 
>>> 1. Mount a X-tal-osc with really lousy tempco inside the enclosure.
>>> 
>>> 2. Compare its output to a stable reference frequency.
>>> 
>>> 3. Use the output of the phase comparator to drive the Peltier.
>>> 
>>> It is basically a PLL where temperature is used as EFC...
>>> 
>>> Has anybody tried that ?
>>> 
>>> -- 
>>> Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
>>> phk at FreeBSD.ORG         | TCP/IP since RFC 956
>>> FreeBSD committer       | BSD since 4.3-tahoe
>>> Never attribute to malice what can adequately be explained by
incompetence.
>>> 
>>> _______________________________________________
>>> time-nuts mailing list -- time-nuts at febo.com
>>> To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>> and follow the instructions there.
>>>     
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at febo.com
>> To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
>> 
>> 
>>   
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

_______________________________________________
time-nuts mailing list -- time-nuts at febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.